WINDOW 8.1 / THERM 8.1 Beta Releases

 

Version 8.1.30

Released: August 13, 2025

WINDOW 8.1.30 and THERM 8.1.30 are the latest versions of our tools that are available for testing. New functionality includes

  • Transient moisture and thermal modeling in THERM
  • Louvered Shutter shading system modeling in THERM and WINDOW

It is not recommended that Beta Version be used for conventional thermal modeling, as it is still in the testing phase.

WINDOW 8.1.30 Beta Version

Installation

It is possible to have both WINDOW / THERM 7 and 8 versions installed on the same computer at the same time.

It is also necessary to install two redistributable libraries, one for Intel Fortran and one for Microsoft Visual C++.

  • IMPORTANT: ***** Redistributable libraries *****
    • If you do not install them, you will get DLL errors when trying to run WINDOW
    • If you have already installed a previous version of WINDOW (such as 7.8) you will not need to install them again.

This version of WINDOW should be used with THERM 8.1

WINDOW 8.1 Installation Files

Link to download WINDOW 8.1 installation files:

  • WINDOW 8.1.30 Setup Full (Window8_1_30_SetupFull.exe)
    • ​Complete installation if you have never installed WINDOW before
  • WINDOW 8.1.30 Setup Small (Window8_1_30_SetupSmall.exe)
    • ​Smaller installation if you have installed previous versions of WINDOW

THERM 8.1.30 Beta Version

Installation

It is possible to have both WINDOW / THERM 7 and 8 versions installed on the same computer at the same time. They are installed in separate folders and can be run at the same time. 

It is also necessary to install two redistributable libraries, one for Intel Fortrain and one for Microsoft Visual C++.

  • IMPORTANT: ***** Redistributable libraries *****
    • If you do not install them, you will get DLL errors when trying to run THERM
    • If you have already installed a previous version of THERM (such as 7.8) you will not need to install them again.

THERM 8.1.30 Installation File

Link to download WINDOW 8 installation files:

Updates / Changes / New Features:

File / Properties Changes

The File / Properties dialog box has expanded to include many more options, all of which are applied to the individual file that is open when they are set. There are 3 new tabs:

  • Calculation Options
    • Simulation Engine - Steady state or Transient
    • Mesh Control - new mesher or original mesher
    • Parameters - setting Radiance mode for THERM-based shading system definitions
      THERM Calculation Options
  • Model Exposure
    • Cross section type settings - Jamb, Sill, Head, and more
    • Gravity vector - should be set automatically based on Cross Section Type, but always check to make sure it is set correctly
      THERM Model Exposure
  • Miscellaneous
    • Float Tolerance
    • Checking Tolerance

New Mesher

THERM has a new mesher which is able to mesh much more complicated geometries, and is set to the default. The old mesher is still available but the new mesher is recommended. The new mesh may result in slightly different results. 

Symmetrix mesher

THERM File Format and Libraries

  • File format is now "THMZ"
    • The THERM file format extension is now THMZ, which represents a zipped file that contains all the necessary library files (now in XML format) that are associated with that THERM file. The THMZ extension can be replaced by the extension "zip" and then the file can be unzipped to see the XML files.
    • To save a THM file (from 7.8.x) to a THMZ file, open the THM file in 8.1 and the program will automatically create the THMZ file, and that will be displayed in the upper left of the THERM window

Sample Sill THMZ

  • Libraries are XML files
    • All the libraries are now XML text files, found in the "lib" subfolder

Library XML files

Modeling Shading Systems with THERM

  • WINDOW User Manual
    • Chapter 19: Modeling Shading Systems: Guidance for modeling Louvered Shutters can be found in Section 19.8. The rest of the manual has been updated to reference the new THERM file format, as well as the new modeling assumption for the non-standard geometry shading systems to only model one element (see below). However, there are probably still sections that have been accidentally omitted from those updates. Please report any wrong information to [email protected].
    • AERC Simulation Manual: The AERC Simulation Manual is in the process of being updated for Louvered Shutters, but is not yet complete. When it has been finished, a link to it will be added here.  
  • Only Model One Element: One change for modeling this type of shading system is that only one element of the system needs to be modeled, ie, one cell in a cellular shade system, or one slat in a louvered shutter system, rather than constructing a stack of cells or slats as previous versions required.

    Only one cell is modeled

Louvered Shutter Modeling

It is possible to model Louvered Shutter shading systems in THERM and WINDOW, in a similar fashion to how cellular shades are modeled. 

  • There are 4 sample Louvered Shutters in the default w8.mdb file that is included in the installation.
  • There are 4 Shading Layers, representing 4 shutter slat tilts.
  • These are then added to 4 glazing systems, one for each tilt, and then those glazing systems are used in 4 window records.
  • In the Window Library, the example Louvered Shutter windows use Generic frames, rather than THERM frames. 

Louvered Shutter Glazing Systems

THERM: Modeling Louvered Shutter Slat Geometry

  • File / Properties menu, Calculation Options tab
    • Simulation Engine: Set to Steady-State Thermal (ConRad)
    • Radiance Mode: Set THERM to be in Radiance Mode

      Calculation Options
       
  • Draw Geometry: Draw the geometry of one louvered shutter slat. Make sure you are in Radiance mode.
    • The material for the slat must be imported from WINDOW based which is measured, and includes optical properties. This is the same methodology as for other shading systems whose geometry is defined by THERM, such as cellular and pleated shades. 

      Louvered Shutter Slat geometry in THERM
       
  • Define Boundary Conditions: There are special Boundary Conditions and U-factor tags for these THERM-based shading systems

    Define Boundary Conditions
  • Exterior Boundary Conditions
    • Boundary Condition: ShadeOutE
    • U-factor Surface tag: ShadeOutETag

Exterior Boundary Condition

  • Interior Boundary Conditions
    • Boundary Condition: ShadeInE
    • U-factor Surface tag: ShadeInETag

Interior Boundary Condition 

  • Calculate: Calculate the model just to make sure that it will mesh

    Calculate the slat model
     
  • Save: Save the model in the desired location

WINDOW: Modeling Louvered Shutter Shading Layers 

  • File / Preferences, Options tab
    • Simulation Engine: Louvered shutters can only be modeled using the WindowsCalc-Engine, set from File /  Preferences, Options tab
    • Tarcog: this is the simulation engine used in WINDOW 7 version

    • WindowsCalc-Engine: this is the simulation engine based on the open source code, Windows-CalcEngine

      WindowsCalcEngine setting

  • Shading Layer Library List View: In the w8.mdb file, the Shading Layer Library contains a set of 4 Louvered Shutter records. There is a different Shading Layer for the same shutter for the standard slat angles of 0, 45, -45, and 90 (which is actually 87 degrees due to the thickness of the slats)

    Shading Layers with Louvered Shutters

  • Shading Layer Library Detail View: The Detail view for each of the Louvered Shutter sample files has the following input values.
    • Type = Louvered Shutter (*.thmz): references a THMZ file (the new THERM format) as well as specifying the slat spacing and the slat tilt.
    • BSDF File: Browse to the THMZ file for the specific Louvered Shutter. These are generally stored in the XML subfolder relative to the location of the WINDOW database (mdb) file.
    • Spacing: Enter the louvered shutter slat spacing
    • Angle: Enter the louvered shutter slat tilt angle.
      • Generally, four angles are modeled for a specific shutter, ie, 0, 45, -45 and 90 (which is generally slightly less than 90 degrees due to the thickness of the slat)
      • The slat angle definition is the same as it is for defining Venetian Blinds, ie, the angle rotation is counter-clockwise.
    • Calculate: Click the Calculate button to generate the genBSDF.XML files. These files will have the same name as the THMZ file, but with a genBSDF.XML extension. They need to be in the same folder as the THMZ file, which by default is an XML subfolder relative to the WINDOW database (mdb file) location. This calculation used to take up to an hour, but now is generated in just a few minutes.

Louvered Shutter Tilt = 45

  • File Locations: Make sure that the THMZ and genBSDF.XML files are in the same folder

    XML files for Louvered Shutters

  • Glazing Systems: Add the Shading Layers to glazing systems, one record for each slat tilt angle, and calculate the results
    • In the Glazing System Detail View, create the glazing system and add the shading system, in this case the louvered shutters defined in the Shading Layer Library
    • Enter the DCenter thickness, which, for a given slat definition, will be the same independent of the slat tilt (which is defined in the Shading Layer). The program will determine the gap thickness between the slat and the glass based on DCenter and the slat tilt, based, as shown below.

      DCenter definition
    • Here is the Glazing System definition for a louvered shutter with slat tilt = 0 degrees (horizontal)

      Glazing System Louvered Shutter Tilt 0
       
    • Here is the Glazing System definition for a louvered shutter with slat tilt = 45 degrees

      Glazing System with Louvered Shutter 45 Tilt
    • Here is the same louvered shutter added to 4 glazing systems, each with a different slat tilt angle

      Louvered Shutter Glazing Systems
       
  • Windows: Add the louvered shutter glazing systems to windows, one record for each slat tilt angle, and calculate the results

Windows with Louvered Shutters

Known Issues

  • THERM-based Shading files
    • For THERM-based shading system files, such as for cellular shades or louvered shutters, if more than one file is open, clicking on the polygon with the shading system material will not show the correct value in the toolbar pulldown list. However, double clicking on that polygon will open the Material dialog box, and the correct material will be displayed. This is not an issue if only one file is opened at a time.

Documentation 

This documentation is from THERM 8.0, which describes the transient modeling, and has not been updated for THERM 8.1. It is provided for context when using the transient model in THERM and will be updated as soon as possible for THERM 8.1